Subject: How can a straight spark be created without an electrolaser?

Instead of a 'chaotic' spark, which kinks around in the air between two charged
points, I want to create a controlled, needle-straight spark.  

I have a high-voltage power supply to work with which came with two needle-point
electrodes.  By 'cheating' and using a length of acrylic tubing between the
charge points, I was able to confine the spark into a relatively straight line.
 But (1) I do not want the spark to be confined by anything but invisible
forces, and (2) I want the spark absolutely straight.

I ask this question not only for its own sake, but to facilitate experiments
which will eventually involve the transmission of electricity in air.  I am
aware that an "electrolaser" can be constructed to do the above, but I am
looking at non-laser-based systems at present.

Re: How can a straight spark be created without an electrolaser?